We have proposed a model to investigate the control mechanisms in regeneration and the expression of polarity. We believe that neurotrophic effects of nerves are due to the production, packaging, and transport of neurosecretory-like granules to the wound site. We propose to isolate and characterize these neurosecretory-like granules by differential centrifugation and then microinject them into the coelom of Sabella to test their ability both to stimulate regeneration and reverse polarity in denervated organisms. We hypothesize that specific morphogenetic effects are mediated by the quantity of granules and thus their active component(s), and further, that their concentration is influenced by the rate of microtubular-mediated transport. We feel that neurotrophic effects are really neurosecretory in nature, a condition that may prove to be a universal feature of nerves. BIBLIOGRAPHIC REFERENCES: Markwald, R.R., T.P. Fitzharris and W.N. Adams Smith, 1975. Structural analysis of endocardial cytodifferentiation. Dev. Biol., 42: 160-180; Cowden, R.R. and T.P. Fitzharris, 1975. The histochemistry and structure of tentacle chondroid tissues in the marine polychaete, Sabella melanostigma. Histochem. Jour., 43:1-10.